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Authorities on Tuesday arrested a suspect accused of making hoax threats to schools, hospitals and a mall, claiming he was armed with an AK-47 and planning to go on shooting rampages. Gerardo Cortez, 26, was booked on suspicion of five counts of making criminal threats and five counts of false report of an emergency, police said. Gadi Schwartz reports from Monrovia for NBC4 News at 11 p.m. on Tuesday, Sept. 17, 2013. (Published Wednesday, Sept. 18, 2013)

Authorities on Tuesday arrested a suspect accused of making hoax threats to schools, hospitals and a mall, claiming he was armed with an AK-47 and planning to go on shooting rampages.

Gerardo Cortez, 26, was booked on suspicion of five counts of making criminal threats and five conts of false report of an emergency, according to a statement from the Arcadia Police Department. Police arrested Cortez as he left his Monrovia home at about 4 p.m.

Prank Calls No Joke to FBI, Local Police

A series of prank calls threatening violence at San Gabriel Valley schools, shopping centers and even a hospital has angered parents and police. The FBI is now assisting local law enforcement agencies in the effort to track down the hoax caller. Patrick Healy reports from Arcadia for NBC4 News at 5 p.m. on Sept. 13, 2013. (Published Friday, Sept. 13, 2013)

Authorities have also served a search warrant on Cortez's home and were continuing their investigation, according to the statement.

At Arcadia High School, the most recently threatened school, administrators received word from police just minutes before the scheduled 2:45 p.m. final bell on Thursday, and responded before the bell rang.

It meant that students, faculty and staff were unable to go home, but instead huddled in rooms with lights turned off for nearly four hours before searching police sounded the all clear.

At one point during the lockdown, another call – believed to have been from the same man who made the initial threat – demanded officers back off, or risk being shot, according to police.

"This guy is getting off trying to scare people," said an Arcadia High School junior who was in her AP Calculus class when the lockdown began. She is also involved on campus with the production of "Apache News," the school's own newscast, and interviewed fellow students and recorded video on her iPhone to be used in her report on the incident.

Santa Fe Middle School in Monrovia was the first school to be threatened on Monday. Duarte High School and adjacent Northview Middle School were threatened the next day.

Other targets of similar, possibly connected hoax threats included Citrus Valley, a family of hospitals with four campuses in three cities, and the Westfield Santa Anita Mall in Arcadia.